Apparatus for the collection and analysis of samples

ABSTRACT

An apparatus for the automatic collection and analysis of fluid samples and particularly for the monitoring of atmospheric pollutants. The apparatus comprises a plurality of traps for the collection of samples and which are in turn exposed for a predetermined time interval to the atmosphere. Thereafter the traps are transferred to an analysis station where pollutant contained in the traps is expelled for analysis into an analytical instrument.

United States Patent [191 Brittan et al.

[ May 8, 1973 [54] APPARATUS FOR THE COLLECTION AND ANALYSIS OF SAMPLES[76] Inventors: Kenneth Walter Brittan, 126 Meadow Lane, Coalsville;James Ephraim Lovelock, Bowerchalke, near Salisbury, both of England 22Filed: Apr. 29, 1971 21 Appl.No.: 138,678

[52] US. Cl. ..73/421.5 R, 23/255 R, 73/28 [51] Int. Cl. ..G01n 1/22[58] Field of Search ..73/42l.5 R, 28;

[56] References Cited UNITED STATES PATENTS 2,489,654 11/1949 Main-Smithet al ..73/421 .5 R X 2,333,934 11/1943 Jacobson ..73/42l.5 R X3,540,261 11/1970 Scoggins ..73/28 FOREIGN PATENTS OR APPLICATIONSAustralia ..73/42l.5 R U.S.S.R. ..73/42l.5 R

Primary Examiner-Louis R. Prince Assistant Examiner-Joseph W. RoskosAttorney-Woodhams, Blanchard & Flynn [57] ABSTRACT An apparatus for theautomatic collection and analysis of fluid samples and particularly forthe monitoring of atmospheric pollutants. The apparatus comprises aplurality of traps for the collection of samples and which are in turnexposed for a pre-determined time interval to the atmosphere. Thereafterthe traps are transferred to an analysis station where pollutantcontained in the traps is expelled for analysis into an analyticalinstrument.

6 Claims, 8 Drawing Figures PATENTEB MAY 8 I973 sumlnrz ATM/P [FYAPPARATUS FOR THE COLLECTION AND ANALYSIS OF SAMPLES The presentinvention relates to an apparatus for the collection of fluid samples.The invention is particularly applicable to the collection of samplesduring pollution studies.

One method of collection is to draw a sample into a bottle or trap bymeans of a pump or suction. The operation is carried out for a definiteperiod of time whereafter the bottle is closed and labelled before beingtransported to a laboratory for analysis. The bottle may contain amaterial which can absorb suspected pollutants in the sample. The methodcan be used for testing gases e.g., atmospheric pollution and fortesting liquids e.g., river pollution.

This known method can become tedious, resulting in operators being proneto error, when a large number of samples are required for a survey. Thepresent invention seeks to provide an apparatus that can sample anenvironment automatically over a selected period of time and which canthereafter be connected to an analytical instrument, such as a gaschromatograph, for the automatic analysis of collected samples.

Thus according to the present invention an apparatus for the collectionof fluid samples comprises a rotatable shaft having fixed for rotationtherewith a carrier for a plurality of sample traps, the traps beingarranged around the axis of rotation of the carrier, valves at theopposite ends of the carrier and in fluid communication with the trapsfor conducting samples into and out of the traps, a recording device forrecording information peculiar to each trap, and a drive connection forrotating the shaft during analysis of collected samples.

In use in the field for the collection of samples the apparatus ismounted in a housing and the shaft is supported for rotation uponjournals. The shaft is rotated by a motor, preferably driven fromelectric batteries contained in the housing. The shaft is rotated tobring each trap in turn into communication with the environment to besampled at selected intervals. Thus, for example, in an apparatus having24 traps, the shaft can be rotated through every hour so that at the endof 24 hours the shaft will have rotated through 360. Conveniently, apump is provided for drawing samples into the traps.

Upon completion of a sampling operation, the apparatus is transferred toan analysis station at which a drive member engages the drive connectionon the shaft to bring each trap successively to a position at which thecollected sample is expelled into an analytical instrument. A masterprogram can be provided to control the operation of the apparatus at theanalysis station. Sample contained in the traps is expelled, as byheating, into the analytical instrument and the signals generated by theinstrument can be recorded on the recording device to provide a recordof the contents of each trap.

The invention thus provides an apparatus which can operate unattended inthe field during the collection of samples and which when transferred toan analysis station for the analysis of the samples can likewisefunction in an automatic manner to record the results.

The invention will be described further, by way of example, withreference to the accompanying drawings, in which:

FIG. I is a diagrammatic section through an apparatus as used forcollecting samples in the field;

FIG. 2 is a diagrammatic section through the apparatus as used at ananalysis station;

FIG. 3 illustrates diagrammatically a valve for controlling the entryand exit of samples into and out of traps;

FIG. 4 illustrates diagrammatically a mounting for traps in a carrier;

FIG. 5 illustrates diagrammatically a heater unit as sociated with thetraps; and

FIGS. 6a, 6b and 6c are diagrammatic sections through the valve of FIG.3 at positions P, Q and R respectively.

A sampling apparatus, illustrated diagrammatically in FIG. 1, is mountedin a housing 10 so as to be readily portable as a unit for location atplaces where samples are to be collected. The housing 10 is preferablyprovided with a lid or cover (not shown) so as to provide a weatherproofenclosure for the apparatus.

The apparatus comprises a motor 1, which can be driven from a batterycontained within the housing, and which is connected to a drive shaft 5by a releasable coupling 2. The drive shafi 5 is rotatably supported ontrunnions 3 and carries a data recording drum 4, selector valves 6 and6' one at each end of a carrier 7 for a plurality of traps and a wormgear wheel 8. Each of the components 4, 6, 6', 7 and 8 is secured to theshaft 5 for rotation therewith. The coupling 2 is such that the shaftcarrying the above components can be released from the motor 1 andlifted out of the housing 10.

For the sake of example only, the carrier 7 supports twenty four trapsdisposed uniformly about the shaft 5 and each trap is exposed by theselector valve 6 adjacent the recording drum 4 to the outside atmospherewhich is being surveyed for pollution. The exposure time for each trapis one hour so that the collector system is able to collect samples overa period of 24 hours. The motor 1 is controlled by a clock to rotate theshaft at the desired rate. It will be appreciated that a pump 21 isprovided so as to draw samples into the traps. The pump is driven by amotor 20 conveniently from the same power source as the motor 1.

Each trap in the carrier 7 may be formed from a glass tube 22 containinga material which will retain a pollutant, the presence of which issuspected in the, atmosphere to be sampled. The glass tube preferablyhas reduced, tapered ends which carry plugs of glass wool to retain thepollutant absorber within the tube. A typical absorber is activatedcharcoal. The glass of the tube is preferably of a heat resistant kind.

The valves 6 and 6' can be a twenty four way sliding valve or a valve ofthe kind as disclosed in British Pat. application No. l3745/70.

In sampling the opening and closing of consecutive traps overlap i.e.,trap 2 will open before closure of trap l; trap 3 will open beforeclosure of trap 2 etc. Upon analysis however, each trap is closed beforethe opening of a second trap. No overlapping of the opening of traps ispermissible. Overlapping is required during sampling to ensure that anevent e.g., a sudden burst of atmospheric pollution is captured in thetrap systems. If this occurs during overlap two consecutive traps willcontain the pollution. If there is no overlap an event could escapedetection. In analysis it is necessary to know when the events occurredand therefore each trap is examined separately. The valve 6 positionedbetween the drum 4 and the carrier 7 and the second valve 6' positionedbetween the carrier 7 and the worm gear 8 are operated together. Inorder to achieve overlapping of traps on the one hand and the separate,discrete opening of each trap on the other hand the valves 6 and 6' areconstructed as indicated diagrammatically in FIG. 3.

Thus each valve 6, 6 can comprise an inner cylinder 30 provided with aplurality of axially extending through bores 31 adjacent the peripherythereof. In the case of an apparatus having 24 traps the inner cylinder30 will be provided with 24 bores 31. Each bore accomodates a resilientconduit 32, such as a silicone rubber conduit, and each axial bore 31communicates with the periphery of the cylinder through a radial bore 33containing a sphere 34. The cylinder 30, which is mounted upon the shaft5, is rotatable within and movable axially relative to an outer cylinderor shell 35.

At position P in FIG. 3 and as shown in FIG. 6a, the shell 35 isprovided with a recess 36 which extends circumferentially over twoadjacent bores 31. At position R in FIG. 3 and as shown in FIG. 60, theshell 35 is provided with a recess 37 which extends circumferentiallyover a single bore 31. At intermediate position Q and as shown in FIG.6b, the shell 35 is not provided with a recess and has a plane innerface.

The operation of the valve 6, 6 is such that when a sphere 34 is out ofalignment with a recess in the inner face of the shell 35, the spheresqueezes closed the resilient conduit 32 accommodated in its associatedbore 31. When a bore 33 is brought into alignment with a recess 36 or 37the sphere 34 therein is moved radially outwards into the recess by theinherent resilience of the tube which is thereby opened.

As shown in FIG. 3, the valves 6, 6 include an inlet or outlet manifold37. Each manifold comprises a chamber having a single inlet or outlet 38and 24 outlets or inlets 39 each connected to a resilient conduitpassing through the bores 31.

At position Q all traps are closed, at position P there is an overlapgroove 36 in outer body 35 whereby two adjacent silicone rubber or likeresilient tubes 32 are opened together over a portion of their totalopening time. At position R there is no overlap and each rubber tube isopened and closed independently of any other tube. To move betweenpositions P, Q, R the shaft or shell 35 is movable axially by means of alever whilst the shell or shaft respectively is held fixed. Thus forsampling the lever is actuated to move valve into position P, foranalysis the valve is moved into position R whilst for transport allvalves are closed with the lever in position 0.

The sampling operation is as follows. The commencement of sampling isrecorded on the drum 4 by an operator who switches on the pump andmotor 1. Thereafter the operation is automatic. As the shaft 5 isrotated the twenty four traps are exposed sequentially at 1 hourintervals and the sampling operation is completed in 24 hours. Theapparatus is arranged to switch off automatically after the exposure ofthe 24 traps. When the carrier is collected, an operator moves the leverto position Q to close all valves for transit to the analysis station.

For analysis of the contents of the traps, the shaft 5 carrying thecomponents 4, 6, 6, 7 and 8 is removed from the housing and placed upona second support having trunnions as shown in FIG. 2. Whereas thesampling takes place in the field, analysis is generally carried out ina laboratory. The worm gear 8 now meshes with a screw 9 whose shaft iscoupled to a master programmer. The master programmer can comprise inputinformation to control an analytical cycle of a gas chromatograph orother analytical instrument and also input information to control thepositioning of the carrier to bring each trap successively into theanalysis position.

Still referring to FIG. 2, a sub-frame 11 supports a heater 1 1A forheating each trap in turn as it is brought beneath the heater uponrotation of the shaft 5. A platform 12 having an aperture 12A therein isarranged above the recording drum 4 to support a data producing means13, for example a printer. The data producing means, which is controlledby signals generated by the analytical instrument (not shown) duringanalysis of the traps, records its output on the drum 4.

An electric motor 40 rotates the screw 9 one revolution at the end ofeach analysis. In the case of the present example having 24 traps theratio between gear wheel 8 and screw 9 is 24:] with the result that eachtrap is moved through 15 upon a complete revolution of the screw 9.

A second motor 42 rotates a spindle 43 through 1 complete revolutionduring each analysis. The motor 42 is driven continuously and thespindle 43 carries a plurality of control cams 44, only two of which areillustrated in FIG. 2. One of the cams 44 serves to control theoperation of the motor 40 and the remaining cams can be utilized tocontrol the functioning of the analytical instrument.

In operation at the analysis station, the screw 9 is driven to rotatethe traps in the carrier 7 successively beneath the heater 1 1A. Uponheating each trap in turn the pollutant which has been trapped thereinis released and is drawn into the analytical instrument for analysis byvirtue of a pressure differential created by a carrier gas employed toconduct the pollutant into the instrument, for example a gaschromatograph. The valves 6 are now in position R. The signal or signalsgenerated by the analytical instrument is or are recorded on the drum 4by the data producing means 13. This operation is repeated for each ofthe traps in the collector system. As mentioned above screw 9 serves torotate the traps beneath the heater as well as being coupled to themaster programmer for the analytical instrument. It is not essential toinclude a data producing means in the apparatus as the signals generatedby the analytical instrument can be noted by an operator and recordedmanually on the drum 4.

FIG. 4 illustrates the mounting of the traps. The carrier 7 comprisestwo end discs 15, 16, having aligned, radial slots at their peripheriesto receive the reduced diameter ends of the traps. The slots areprovided with a resilient cushion or support for the traps. The trapsare retained in position by retaining clips 45 which are secured to thediscs, one adjacent each end of each trap. A conduit 20A is shown inFIG. 4 leading from a trap to valve 6.

Each trap 22 is situated within a heat reflector 18 of a polished metalsuch as aluminum or stainless steel.

The reflector l8 co-operates with a similar reflector forming part ofthe heater 11A. The two reflectors together form a reflector assemblyhaving an elliptical section in a plane transverse to the longitudinalaxis of a trap. The trap is located at one focus of the ellipticalassembly and a heater element 45 is located at the other focus. Theheater element 45 is preferably a radiant heater bar extending thelength of the trap. FIG. 5 illustrates diagrammatically the arrangementof the reflectors in the heater unit and carrier. During analysis, eachtrap is brought in turn beneath the heater element. A heating current toheat the element may be determined by the master programmer in order toheat the traps at the required time in the analysis cycle. Radiationheating is preferred due to infra-red radiation penetrating the glasswalls of the trap and being quickly absorbed by the material, e.g.,activated char coal in the trap. However other modes of heating thetraps are possible and the invention is not limited to radiationheating.

Whilst 24- traps have been given in example with reference to thedrawings, it will be appreciated that the number of traps can beadjusted to suit particular requirements.

Silicone rubber is but an example of a suitable material for theresilient conduits of the valves 6, 6'. The conduits can each be formedfrom a composite tube having an outer silicone rubber tube lined with aplastics sheath, such as P.T.F.E. The plastics sheath will be bonded tothe bore of the silicone rubber tube.

The apparatus is suitable for use with gases. For example, the apparatuscan be used in air pollution studies in which a tracer gas is releasedinto the atmosphere and recorded by arrays of sampling traps atdifferent location.

We claim:

1. Apparatus for collecting fluid samples in the field and forpresenting the collected samples at an analysis station comprising arotatable shaft, a carrier secured for rotation with the shaft, aplurality of sample traps supported by the carrier, a pair of valveassemblies mounted on the shaft one at each end of the carrier, eachvalve assembly comprising a plurality of valve members operable to openand close upon rotation of the shaft and with one member of eachassembly connected to and associated with one only of the traps wherebyeach trap is opened and closed in succession upon rotation of the shaft,means for drawing samples into the traps and first drive means forrotating the shaft at the field station, second drive means for rotatingthe shaft and means for expelling the collected samples from the trapsat the analysis station.

2. An apparatus as claimed in claim 1 in which the fust drive meanscomprises a motor controlled by a clock and connected to the shaft by areleasable coupling.

3. An apparatus for the collection and analysis of fluid samplescomprising a rotatable shaft, a carrier for a plurality of sample trapsfixed for rotation with said shaft, a pair of valve assemblies mountedon the shaft one at each end of the carrier for controlling flow ofsamples into and out of the opposite ends of the traps, a first driveconnection for rotating the shaft during collection of samples, and asecond drive connection for rotating the shaft during analysis ofcollected samples the second drive connection comprising a gear w eel onthe shaft engageable with an intermittently driven worm gear, the driveto said worm gear being controlled by a programmer whereby each trap inturn is moved through a sample release station.

41. An apparatus as claimed in claim 3 in which the sample releasestation includes a heater disposed adjacent the carrier.

5. An apparatus as claimed in claim 4 in which each trap is situatedwithin a heat reflector, each heat reflector co-operating in turn with aheater reflector about the heater to form an elliptical assembly in aplane transvere to the longitudinal axis of a trap, each trap beinglocated at one focus of the elliptical assembly and the heater beinglocated at the other focus of the assembly.

6. An apparatus for the collection and analysis of fluid samplescomprising a rotatable shaft, a carrier for a plurality of sample trapsfixed for rotation with said shaft, a pair of valve assemblies mountedon the shaft one at each end of the carrier for controlling flow ofsamples into and out of the opposite ends of the traps, a first driveconnection for rotating the shaft during collection of samples, and asecond drive connection for rotating the shaft during analysis ofcollected samples, each valve assembly including a manifold and innerand outer valve members, the inner valve member having a plurality ofaxially extending bores each accommodating a resilient conduit connectedto the manifold, a radial bore extending from each axially extendingbore to the periphery of the inner valve member and accommodating avalve closure member, the inner valve member being rotatable within theouter valve member and axially movable relative to the outer valvemember and recesses in the outer valve member to receive the valveclosure member at selected angular positions of the inner valve memberwhereby to enable the resilient conduits to expand to permit sample flowtherethrough.

1. Apparatus for collecting fluid samples in the field and forpresenting the collected samples at an analysis station comprising arotatable shaft, a carrier secured for rotation with the shaft, aplurality of sample traps supported by the carrier, a pair of valveassemblies mounted on the shaft one at each end of the carrier, eachvalve assembly comprising a plurality of valve members operable to openand close upon rotation of the shaft and with one member of eachassembly connected to and associated with one only of the traps wherebyeach trap is opened and closed in succession upon rotation of the shaft,means for drawing samples into the traps and first drive means forrotating the shaft at the field station, second drive means for rotatingthe shaft and means for expelling the collected samples from the trapsat the analysis station.
 2. An apparatus as claimed in claim 1 in whichthe first drive means comprises a motor controlled by a clock andconnected to the shaft by a releasable coupling.
 3. An apparatus for thecollection and analysis of fluid samples comprising a rotatable shaft, acarrier for a plurality of sample traps fixed for rotation with saidshaft, a pair of valve assemblies mounted on the shaft one at each endof the carrier for controlling flow of samples into and out of theopposite ends of the traps, a first drive connection for rotating theshaft during collection of samples, and a second drive connection forrotating the shaft during analysis of collected samples, the seconddrive connection comprising a gear wheel on the shaft engageable with anintermittently driven worm gear, the drive to said worm gear beingcontrolled by a programmer whereby each trap in turn is moved through asample release station.
 4. An apparatus as claimed in claim 3 in whichthe sample release station includes a heater disposed adjacent thecarrier.
 5. An apparatus as claimed in claim 4 in which each trap issituated within a heat reflector, each heat reflector co-operating inturn with a heater reflector about the heater to form an ellipticalassembly in a plane transvere to the longitudinal axis of a trap, eachtrap being located at one focus of the elliptical assembly and theheater being located at the other focus of the assembly.
 6. An apparatusfor the collection and analysis of fluid samples comprising a rotatableshaft, a carrier for a plurality of sample traps fixed for rotation withsaid shaft, a pair of valve assemblies mounted on the shaft one at eachend of the carrier for controlling flow of samples into and out of theopposite ends of the traps, a first drive connection for rotating theshaft during collection of samples, and a second drive connection forrotating the shaft during analysis of collected samples, each valveassembly including a manifold and inner and outer valve members, theinner valve member having a plurality of axially extending bores eachaccommodating a resilient conduit connected to the manifold, a radialbore extending from each axially extending bore to the periphery of theinner valve member and accommodating a valve closure member, the innervalve member being rotatable within the outer valve member and axiallymovable relative to the outer valve member and recesses in the outervalve member to receive the valve closure member at selected angularpositions of the inner valve member whereby to enable the resilientconduits to expand to permit sample flow therethrough.